Refrigeration apparatus for air conditioning systems



Sept. 21, 1943. M. E. HANSON REFRIGERATION APPARATUS FOR AIR CONDITIONING SYSTEMS Filed Oct. 9, 1941 w mm am am Vm uumaow mm uatumfi 832188 3 1 MW J n \wm, Q an I: vn hm N\ mm b@ Mm m m w m x Q U H u Q Q\. Q U h & |HHDH.. N ll 1 III] Patented Sept. 21, 1943 CONDITIONING SYSTEMS Milton E. Hanson, Haddonfield, N. J assignor to B. Sturtevant'Gompany, Boston, Mass.

Applicationgoctober 9, 1941, Serial No; 414,3 1!

' recirculated, air from the passenger space,

' 2 Claims.

This invention relates to refrigeration apparatus and relates more particularly to refrigeration apparatus for the cooling of air in air conditioning systems;

In air conditioning systems such, forexample,

as'those for railway passenger cars, it is necessary to operate the refrigeration equipmentun der varying loads. The usual system uses a direct expansion evaporator for cooling the air with a car thermostat for stopping and starting the compressor. Such' systems have several great disadvantages. One isthat the'air is either; too hot or too cold since either none or all of the equipment is active. Another is that the wear on the compressoris great due to the frequent starts and stops- Still another is that the moisture condensed on the evaporator during operation of the. compressor, is reevaporated into the air stream when the compressor is idle, it

being the practice to keep the fans operating continuously.

This invention provides an air cooling evaporator with its tubes extending crosswise the air stream divided into two groups, the tubes of the two groups being alternately arranged and extending through common extended surfacefins. One group preferablyhas. the smallest, number of tubes and is arranged to be rendered inactive when the temperature in the car is that desired, by the closing of a valve in between its suction header and the compressor. The other group continues in operation and if the temperature within the car falls too low, the car thermostat decreases the supply of refrigeration to the evaporator as by partially unloading the compressor or by decreasing its speed. 7

Advantages of this invention are that the air stream is chilled at all times; that most of the cycling takes place on a single simple valve which renders one evaporator section inactive, and that by controlling the number of active evaporator sections by one or more valves in the suction line, any form of refrigerant supply means to the evaporator may be employed.

Objects of the invention areto improve the performance of, and to simplify the construction of, air cooling, refrigerant evaporato'rs.

The invention will now be described with reference to the drawing which illustrates diagrammatically one embodiment of this invention.

The railway car 5 has mounted above the passenger space, the blower 6, the air conditioning structure 1 including the air cooling evaporator 8, and the air distributing duct 9. The blower 6 draws in outdoor air through the inlet l0, and

through the inlet H.

The evaporator 8 contains a plurality of hori zontal tubes I2 arranged in vertical and horizontal rows. The header l3 connects with all of the tubes of the front rows, with respectto air flow. In the embodimentillustrated there are ten vertical rows of tubes. The rear tubes of-the first, third, fifth and seventh rows are connected to the suction headerlt whilethe rear tubes of the second, fourth, sixth, eighth, ninth and tenth rows are connected to the suction header Hi.

:The plurality of closely spaced verticalfins It as is usual, extend around and in contact with all of the tubes and form common interconnecting heat exchange surfaces. The suction header i5 is connected by the tube l to the suction side of the compressor and thesuction header M; is connected through the valve I8 to the tube Ill. The solenoid l9 controlled by the car thermostat 20 vactuates the valve It as will be described; t The compressor 2| driven by themotor 22, supplies refrigerant through the valve 23, condenser 24 and expansion valve 25 to the inlet header l3. Y

The by-pass tube 26 connects with the suctiontube l'l-and with the two way valve 23 between the compressor and condenser. When the valve 23 is adjusted to one position by the solenoid 21, the inlet of the valve 23 connecting with the tube 23 is closed and all of the refrigerant flows through the compressor to the condenser. When the valve 23 is adjusted to its other position, the inlet of the valve 23 connecting with the tube 26 is partially opened, and the outlet of the valve 23 connecting with the condenser is partially closed so that the compressor is partially unloaded through a portion of the refrigerant being recirculated through the compressor.

The thermostat20 is a standard mercury column thermostat with a contact 3| contacting the mercury in the column of the thermostat; with the contact 32 extending into the stem at the 72 F. point, and with the contact 35 extending into the stem at the 68 F. point. The thermostat controls two circuits. At temperatures above 68 F. but below 72 F., one circuit including the elec tric source 28, the wire 30, the contact 3f, the mercury column in the thermostat, the contact 35, the wire 36, the solenoid 21 and the wire 31, is closed for energizing the solenoid 2! for actuating the valve 23 for loading the compressor. During this time, the other circuit including the solenoid I9 is not closed since the mercury column has not reached the contact 32.

When the temperature rises above 72 F., the circuit including the electric source 28, the wire 30, the contacts 3| and 32, the mercury column, the wire 33, the solenoid l9, and the wire 34 is closed, thus energizing the solenoid I9 to render one of the groups of evaporator tubes inactive. Both circuits are'thus closed at this time.

When the temperature falls below 68 F., the

above described circuit includin the solenoid 21 is open and the solenoid 21 is deenergized and adjusts the valve 23 to unload the compressor. Both circuits are open at this time.

In operation, when the car temperature has. dropped to the desired level which for example, I

may be 72 F., the thermostat 29 opens the circuit including the solenoid l9'-and the electric source 28, causing the valve it to close and the group of evaporator tubes consisting of the first, third, fifth and seventh vertical rowsof tubes to become inactive. The other group remains active and due to the positioning of the tubes of .this other group completely across the air stream, and due to the interconnecting fins, the entire air stream is chilled and no reevaporation of'previously condensed moisture, from the surface of the inactive tubes can take place.

If the temperature falls below' the minimum desired which for example, may be 68 F., the thermostat 20 opens the circuit including the electric source 28 and the solenoid 21 causing the valve 23 to be adjusted for recirculation of refrigerant through the by-pass tube 26. .The compressor continues in operation without the wear caused by the usual frequent cycling thereof.

Depending upon the refrigerant used and perhaps other factors, other well known means of supplying refrigerant to the evaporator may be used instead of that illustrated. For example, the usual Freon capillary tube distributors such for example as disclosed in the Morton Reissue Patent No. 20,964 may be used. I

The evaporator is preferably divided into a small and a large group so that the small group may be rendered inactive during peak loads, with the large group in service the remainder of the time, thus more advantageously utilizing the equipment.

While one embodiment of the invention has been described for the purpose of illustration, it

should be understood that the invention is not limited to the exact apparatus and arrangement of apparatus described since modifications therefrom may be suggested bythose skilled in the art without departure from the ,essence "of the invention.

What is claimed is:

1. Refrigeration apparatus for air cooling comprising an evaporator having air contacting tubes placed in superimposed parallel rows, said tubes 5- being divided into two groups, tubes of said groups being arranged; in alternate rows, extended surface fins in contact with all of said tubes, a suction header connected to the tubes of one of said groups, a second suction header connected to the tubes of the other of said groups, means including a compressor for supplying refrigerant to all of said tubes, suction lines connecting said headers and said compressor, a valve in one of said lines for preventing the flow of refrigerant 25 through the tubes of one of said groups, and

prising an evaporator having air contacting tubes placed in superimposed parallel rows, said tubes being divided into two groups, tubes of said groups being arranged in alternate rows, extended surface fins incontact with all of said tubes,-the

tubes of one ofsaid groups being fewer in numher than those of the other of said groups, a suction header connected to the tubes of one of said groups, a second suction header connected to the tubes of the other of said groups, means including a compressor for supplying refrigerant to all of said tubes, suction lines connecting said headers and said compressor, a valve in one of said lines for preventing the flow of refrigerant through the tubes of said one of said groups, and means responsive to a change in condition brought about 

